A two-sided assembly line is typically found in plants producing large-sized products. Its advantages over a one-sided line and the difficulties faced in two-sided line balancing problems were discussed. A mathematica...A two-sided assembly line is typically found in plants producing large-sized products. Its advantages over a one-sided line and the difficulties faced in two-sided line balancing problems were discussed. A mathematical model for two-ALB problem was suggested. A modification of the “ranked positional weight” method, namely two-ALB RPW for two-ALB problems was developed. Experiments were carried out to verify the performance of the proposed method and the results show that it is effective in solving two-sided assembly line balancing problems.展开更多
The fast growth of Internet has cre-ated the need for high-speed switches. Re-cently, the crosspoint-queue switch has at-tracted attention because of its scalability and high performance. However, the Cross-point-Queu...The fast growth of Internet has cre-ated the need for high-speed switches. Re-cently, the crosspoint-queue switch has at-tracted attention because of its scalability and high performance. However, the Cross-point-Queue switch does not perform well under non-uniform traffic. To overcome this limitation, the Load-Balanced Cross-point-Queued switch architecture has been proposed. In this architecture, a load-balance stage is placed ahead of the Cross-point-Queued stage. The load-balance stage transforms the incoming non-uniform traffic into nearly uniform traffic at the input port of the second stage. To avoid out-of-order cells, this stage employs flow-based queues in each crosspoint buffer. Analysis and simulation results reveal that under non-uniform traffic, this new switch architecture achieves a delay performance similar to that of the Out-put-Queued switch without the need for inter- nal acceleration. In addition, its throughput is much better than that of the pure cross- point-queued switch. Finally, it can achieve the same packet loss rate as the cross- point-queue switch, while using a buffer size that is only 65% of that used by the cross- point-queue switch.展开更多
In this note, we would like to point out that （i） of Corollary 1 given by Zhang et al. （cf Commun. Theor. Phys. 39 （2003） 381） is incorrect in general.
The asymptotic behavior of the time-dependent solution for a 3-species cooperating model was investigated with the effects of both diffusion and time delay taken into consideration. We proved the global asymptotic sta...The asymptotic behavior of the time-dependent solution for a 3-species cooperating model was investigated with the effects of both diffusion and time delay taken into consideration. We proved the global asymptotic stability of a positive steady-state solution to the model problem by using coupled upper and lower solutions for a more general reaction-diffusion system that gives a common framework for 3-species cooperating model problems. The result of global asymptotic stability implies that the model system coexistence is permanent. Some global asymptotic stability results for 2-species cooperating reaction-diffusion systems are included in the discussion, and some known results are extended.展开更多
The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this paper.The mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change process.T...The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this paper.The mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change process.That is to say energy is required to overcome the potential barrier when the new interface is formed from primary phase.The superheat of liquid is the impetus of phase change and has an exponential decrease with the increase of the saturated temperature of fluid.The analysis also indicates that there is a critical radius during the phase change process.The bubble will grow up when its radius is larger than the critical value,otherwise,will disappear.When considering the metastable phase change,calculation of P and V during expansion process indicates that the phase-change will be delayed with the decline of pressure,which is called lag phenomenon.The phase-change delay time decreases with the increase of initial temperature.When the initial temperature is close to the critical temperature,the delay time is close to zero.The phase-change delay brings energy losses,which decrease with the increase of initial temperature and its decrease ratio also has a decrease trend.When the initial pressure is 10 MPa,the energy loss will be 1.06 W with an initial temperature of 10℃ while 0.34 W with that of 20℃.展开更多
A dynamic model of schistosoma japonicum transmission is presented that incorporates effects of the prepatent periods of the different stages of schistosoma into Baxbour＇s model. The model consists of four delay diff...A dynamic model of schistosoma japonicum transmission is presented that incorporates effects of the prepatent periods of the different stages of schistosoma into Baxbour＇s model. The model consists of four delay differential equations. Stability of the disease free equilibrium and the existence of an endemic equilibrium for this model are stated in terms of a key threshold parameter. The study of dynamics for the model shows that the endemic equilibrium is globally stable in an open region if it exists and there is no delays, and for some nonzero delays the endemic equilibrium undergoes Hopf bifurcation and a periodic orbit emerges. Some numerical results are provided to support the theoretic results in this paper. These results suggest that prepatent periods in infection affect the prevalence of schistosomiasis, and it is an effective strategy on schistosomiasis control to lengthen in prepatent period on infected definitive hosts by drug treatment （or lengthen in prepatent period on infected intermediate snails by lower water temperature）.展开更多
In this paper, an SIRS epidemic model with time delay and vaccination is investigated. By analyzing the corresponding characteristic equation, the local stability of diseasefree equilibrium of the model is established...In this paper, an SIRS epidemic model with time delay and vaccination is investigated. By analyzing the corresponding characteristic equation, the local stability of diseasefree equilibrium of the model is established. By constructing Lyapunov functional, sufficient conditions are established for the local stability of an endemic equilibrium of the model. Further, a threshold value is obtained. By using comparison arguments, it is proved when the threshold value is less than unity, the diseasefree equilibrium is globally asymptoti cally stable. When the threshold value is greater than unity, by using an iteration scheme and by constructing appropriate Lyapunov functional, respectively, sufficient conditions are derived for the global stability of the endemic equilibrium of the model. Numerical simulations are carried out to illustrate the theoretical results.展开更多
基金Key Projectof Scientific and TechnologicalCommittee of Shanghai(No.0 3 11110 0 5 )
文摘A two-sided assembly line is typically found in plants producing large-sized products. Its advantages over a one-sided line and the difficulties faced in two-sided line balancing problems were discussed. A mathematical model for two-ALB problem was suggested. A modification of the “ranked positional weight” method, namely two-ALB RPW for two-ALB problems was developed. Experiments were carried out to verify the performance of the proposed method and the results show that it is effective in solving two-sided assembly line balancing problems.
文摘The fast growth of Internet has cre-ated the need for high-speed switches. Re-cently, the crosspoint-queue switch has at-tracted attention because of its scalability and high performance. However, the Cross-point-Queue switch does not perform well under non-uniform traffic. To overcome this limitation, the Load-Balanced Cross-point-Queued switch architecture has been proposed. In this architecture, a load-balance stage is placed ahead of the Cross-point-Queued stage. The load-balance stage transforms the incoming non-uniform traffic into nearly uniform traffic at the input port of the second stage. To avoid out-of-order cells, this stage employs flow-based queues in each crosspoint buffer. Analysis and simulation results reveal that under non-uniform traffic, this new switch architecture achieves a delay performance similar to that of the Out-put-Queued switch without the need for inter- nal acceleration. In addition, its throughput is much better than that of the pure cross- point-queued switch. Finally, it can achieve the same packet loss rate as the cross- point-queue switch, while using a buffer size that is only 65% of that used by the cross- point-queue switch.
文摘In this note, we would like to point out that （i） of Corollary 1 given by Zhang et al. （cf Commun. Theor. Phys. 39 （2003） 381） is incorrect in general.
基金the Academic Mainstay Cultivate Foundation of Sichuan Province under the grant No.1200311.
文摘The asymptotic behavior of the time-dependent solution for a 3-species cooperating model was investigated with the effects of both diffusion and time delay taken into consideration. We proved the global asymptotic stability of a positive steady-state solution to the model problem by using coupled upper and lower solutions for a more general reaction-diffusion system that gives a common framework for 3-species cooperating model problems. The result of global asymptotic stability implies that the model system coexistence is permanent. Some global asymptotic stability results for 2-species cooperating reaction-diffusion systems are included in the discussion, and some known results are extended.
基金supported by the National Natural Science Foundation of China (Grant No 50676064)
文摘The expansion mechanism inside carbon dioxide expander is analyzed theoretically in this paper.The mechanism analysis of metastable equilibrium indicates that there is a potential barrier during phase change process.That is to say energy is required to overcome the potential barrier when the new interface is formed from primary phase.The superheat of liquid is the impetus of phase change and has an exponential decrease with the increase of the saturated temperature of fluid.The analysis also indicates that there is a critical radius during the phase change process.The bubble will grow up when its radius is larger than the critical value,otherwise,will disappear.When considering the metastable phase change,calculation of P and V during expansion process indicates that the phase-change will be delayed with the decline of pressure,which is called lag phenomenon.The phase-change delay time decreases with the increase of initial temperature.When the initial temperature is close to the critical temperature,the delay time is close to zero.The phase-change delay brings energy losses,which decrease with the increase of initial temperature and its decrease ratio also has a decrease trend.When the initial pressure is 10 MPa,the energy loss will be 1.06 W with an initial temperature of 10℃ while 0.34 W with that of 20℃.
基金supported by the National Natural Science Foundation of China(Nos.10831003,10925102)the Program of Shanghai Subject Chief Scientist(No.10XD1406200)
文摘A dynamic model of schistosoma japonicum transmission is presented that incorporates effects of the prepatent periods of the different stages of schistosoma into Baxbour＇s model. The model consists of four delay differential equations. Stability of the disease free equilibrium and the existence of an endemic equilibrium for this model are stated in terms of a key threshold parameter. The study of dynamics for the model shows that the endemic equilibrium is globally stable in an open region if it exists and there is no delays, and for some nonzero delays the endemic equilibrium undergoes Hopf bifurcation and a periodic orbit emerges. Some numerical results are provided to support the theoretic results in this paper. These results suggest that prepatent periods in infection affect the prevalence of schistosomiasis, and it is an effective strategy on schistosomiasis control to lengthen in prepatent period on infected definitive hosts by drug treatment （or lengthen in prepatent period on infected intermediate snails by lower water temperature）.
文摘In this paper, an SIRS epidemic model with time delay and vaccination is investigated. By analyzing the corresponding characteristic equation, the local stability of diseasefree equilibrium of the model is established. By constructing Lyapunov functional, sufficient conditions are established for the local stability of an endemic equilibrium of the model. Further, a threshold value is obtained. By using comparison arguments, it is proved when the threshold value is less than unity, the diseasefree equilibrium is globally asymptoti cally stable. When the threshold value is greater than unity, by using an iteration scheme and by constructing appropriate Lyapunov functional, respectively, sufficient conditions are derived for the global stability of the endemic equilibrium of the model. Numerical simulations are carried out to illustrate the theoretical results.
